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formed of two pieces of timber hinged at the edge below. They are kept asunder above by a plate of wood B. " At different distances on the plate B are slips (shown apart, at C), which serve to keep open the wedge at different angles.

Froin a roller at either side of the wedge passes a cord to a pulley, placed level with the rollers, and fastened as may be convenient; for instance, to the window and door trimmings of a room. The (frame / f and base D with blocks b b are only to keep the wedge and rollers in position nntil the weights W W are hung npon the cords, and P placed upon the "back of the wedge." A convenient sort of weights for this apparatus are jars (see figure); they are in themselves heavy and can be well proportioned by water, which will also serve to increase their general weight. Thus prepared, a series of experiments may be exhibited with the apparatus.

Experiment I.—Fix the wedge at its smallest angle, make P (at a guess) somewhat heavier than |shall be required for equilibrium, when the heavy weights W W are allowed to act. Let W W act. By "feeling" the wedge (raise it a little) it will appear whether P is, or not, too heavy. If it be too heavy remove some of the water (in P) until P shows no tendency to push the wedge down. One block 6 may now be removed (the second is left for fear of any accidental slip down of the wedge), equilibrium is completely established, and the great power of the ■wedge may be somewhat estimated by the difference of the weight P, and the sum of W W. This experiment will be more striking if the base with supporting frame be removed (drawn down from under the rollers); there is then nothing to meet the eye but the forces in equilibrated action.

Experiment II.—Restore block b, stop the action of W W (by any convenient method—a second cord, a block, &c, to each), remove P, and open the wedge ito next pair of slips) wider. Replace P, hold if on the "back" by additional weight or otherwise; allow W W to act. The weight of P in the first experiment is no longer able to command W W; the wedge is pushed up if the holding force on P bo diminished still more ; if it be maidenly removed, the wedge may be suddenly Bhot out from between the rollers. Should this exciting conclusion be intended, there must be some provision for saving the wedge, &c. from injury. The experiment may be continued by pouring water into P until the now broader wedge is in equilibrium. Remove P, open the wedge still wider, replace P, &c.; again the same action of W W as above. Thus is shown experimentally the great practical principle of the wedge, " that the smaller the angle the better the action."

Experiment III.—Make W W as heavy as the cords can safely bear, open the wedge wide, and

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I Ky ii mistakes of the engraver the diagi »m is not made sufficiently clear. The cords should Pass to the roller farthest removed from it—that is, the cords from P should act on the right-hand roller as you look at the engraving, nod the cor/' f; nm P- act on the left-hand roller.

place on its back a P sufficient for equilibrium. When W W are allowed to act, the strain on the cords (which will perhaps even render a musical note if made to vibrate) gives a good idea of the intense resistance of a body to the splitting action of a wedge. This "impression" of force, becomes startling by removing quickly the cap of the wedge; the two plates, A A, slap together with a violence which gives a most appreciable proof of the very great force that the wedge had resisted.

Wedge App. I.—Cutting Instruments.—As these are all wedges, single or double, they work better or worse as the practical principle is more or less observed. Therefore the finer the edge, i.e., the longer the edge, the better. The limits of reducing the cutting angle must be ruled by the work to be done. The harder, tougher, <fcc, the material, the wider must be the limiting angle, for the wedge of the cutting instrument having to overcome a greater opposition requires more of its own particles in the line of action to bear against the increased resistance.

Wedge App. II.—Tiie Arch.—This very important element of architecture, would require, to do it justice, knowledge beyond the present reach of the student; a good notion then of its principle of action must suffice. [In general terms, therefore, it may be said to consist of a number of wedges so laid together, that the force from their own weight, and from any weight that may be superadded, is transferred to, and opposed by, an infinite resistance, or what in the possible circumstances is equivalent to an infinitive resistance. By infinitive resistance is to be understood a resistance capable of permanently arresting the action of the force under consideration. In regard of this force such a resistance is practically infinite.

The wedges which compose tho arch A, Fig. 83, arc called the roussoirs, a a . . . Of these the chief is the centre one, A, commonly called the key-stone. The voussoirs start at either side from what are called the abutment*, B B. Now, supposing the materials capable of resisting as long as the weight of the voussoirs, a a . . .— and whatever weight may be added above— passes to the abutments, the arch is safe. But if the resultant of the forces pass outside the line of the abutments, the resultant may take effect— the arch may be buret in, out, or up—the voussoirs, (the wedges) yielding as in No. II. of the wedge experiments. Fortunately this giving way is to a certain extent prevented by the surfaces of building materials. These surfaces within limits of certain angles will not slide one over the other. These "sliding angles " being well known enter into the calculation of the stability of a given arch, which, consequently, may still be safe though the forces (the pressures) act slightly along a line not passing to the abutment. In thus considering the arch as made up of wedges, it is clear that I' is not the wedge as a machine, but the reverse that is required. In the arch the wedges are to be in equilibrium such that motion be impossible.

Sub. Apr. II.—The Screw.—There is nothing in the essentials of an inclined plane which requires that its direction shoull be a straight line. It may, therefore, wind round it until the "height" and "point" are on the same perpendicular A B (Fig. 84).

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regarding this "machine." Let an inclined plane be wound round a cylinder until the "height and point" meet as above. There is thus formed one turn of the screw. From the top of the "height" the same plane starts again, and winding, as before, produces the second tem of the screw. In the same way the 3rd, 4th, .... nth turn; in a word, the whole screw is constructed. It may then be described as a perpendicular series of inclined planes having the same " height and base " wound consecutively round a cylinder.

Two " essentials " of the inclined plane change their name in the screw (Fig. 85). The height is called the "pitch," a a, the distance between two turns; the length is called the "thread" or "icorm" of the screw. The "base" has no special name in the screw, but is represented by the circumference of the cylinder on which the thread or worm is rolled. The action of the screw is that of the inclined plane. The force which it has to resist is frequently not that of gravitation; but tho force, whatever it be, is always applied, as gravitation is applied on the inclined plane. The action of the resisting force is usually exerted by what is called a nut, This nut is a hollow inclined plane of the same pitch as the thread of the screw. As the nut covers usually two or more turns of the screw, the real action of the machine is concealed, and may be not clearly understood. All confusion will be removed by a return to the inclined plane (Fig. 86). Instead of the weight being placed upon a small space, a b. suppose it (the same

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THE MITRAILLEUR.

THIS weapon, of which we have heard so much lately, is but an improvement of an old idea. In the Hotel de Cluny, at Paris, there is a carbine with several barrels constructed upon the principle of the revolver, which is said to have belonged to Charles IX. or Henry III. of France, but certainly dating from the period of the Massacre of St. Bartholomew. In a work on "Weapons of War," by M. Auguste Demmin, translated by Mr. C. C. Black, Assistant-Keeper of the South Kensington Museum, appears the following account of what is now called the Mitrailleur, or Mitrailleuse :—

It is very difficult, in fact almost Impossible, to classify exactly, according to the names then la use, all the different species of cannon, for very often tho same piece was named differently in each large city. L'orgue a eernentiru, which was a machine composed of a great number of guns of Btuall bore, loadod either from the muzzle or at the breech, had each separate chamber encased as far as the muzzle in wood or metal: the chambers wero fired in succession orallatonce. In Germany they were called Todtenorgel (death-organ). Welgel. writing in 1698, says that in the arsenal at Nuremberg there were organs with thirty-three pipes to them, and that death might be said to play dance music on them. One of the earliest of these machines is in the museum at Sigmaringen. It was made at the beginning of the fifteenth century. It is loaded from tho muzzle, and is composed of small npright iron cannons rudely mounted on what looks like tho trunk of a tree, and moves on two round discs of wood for wheels. Another of these machines, termod Orgue de danse Macabre, copied in 150;i by NicolauB Glockcnthon from one of the arsenal*, of the Emperor Maximilian, is composed of forty squareshaped tubes firmly joined together and mounted on a stand with large wheels somewhat similar to the carriage of a field-piece. A third one, of the seventeenth century, consisting of forty-two barrels, mounted so as to form a triangular block, aud to fire Bix successive volleys, is now in the museum at Soleurc. From £tuaW Mir VArtillerie, by Napoleon III., published in 1846, it will he seen that there were some of these machines which could fire 140 shots at once.

Similar weapons to these are, we believe, to be seen in the Tower, but they all lack the distinguishing characteristic of the Mitrailleur— rapidity of fire, or rather of continuous fire.

The Montigny (or "Christophi-Montigny") mitrailleur, now under trial in this country, is a Belgian invention, and although similar to the French weapon in construction, is supposed to be superior Jto it in mechanical detail. In appearance it resembles an ordinary field-gun with

a greatly enlarged breech-piece; but on looking nt tlie muzzle, instead of a single bore, we find 37 holes, each about {in. in calibre. These holes appear aB if bored into the solid gun, but in reality, 37 hexagonal steel barrels are fitted accurately together, and soldered into a thin external wrought-iron tube. This tube has a movable breech action, worked by ineaus of a lever, and containing a spiral spring and striker for each barrel. The cartridges are placed in a movable steel breech-plate, baring us many holes as there are barrels. This plate is introduced into its place at the breech, which is then closed and secured by the lever. By means of a handle resembling that of a barrel-organ, the 37 cartridges can be tired independently, and as slowly as may be desired; or by a rapid turn of the wrist, the whole number can be tired almost simultaneously, the time occupied beiug one second. The empty plate can be replaced by one ready rilled in the space of five seconds; and a continuous tire, at the rate of ten discharges per minute maintained, being equal to 370 shots; and as each bullet weighs 600 grains, this gives something over 311b. of lead per minute. The tire can be concentrated on one spot (the piece having but little recoil), or by means of a horizontal or mowing movement the tlight of the bullets can bo altered between each discharge, or during the discharge itself, so as to spread it over a wide front, somewhat in the manner of a fan. The mitrailleuris effective up to 1,000 yards. Its weight is only 4001b. ; it is rilled on the Metford system. The bullet which is hardened, weighs 600 grains, and the charge of powder is 115 grains. The exact calibre is 534in., and the cartridge may be either Boxer or metallic, as preferred. The mean absolute deviation at a range of 500 yards is 31in.; mean angle of elevation 1' 24". At S00 yards, the mean absolute deviation is 51in.. and the elevation, 2° 5", whilst at 1,000 yards, it is '2 35". The Gatling gun, in the possession of the Prussians, is a heavier weapon, and partakes more of the character of artillery. It contains ten barrels of a calibre sufficient to throw lin. shot or shell to considerable distances. In the matter of loading and tiling it is somewhat similar to the Montiguy and the French mitrailleur. Whether these weapons will have the extraordinary effect expected of them remains to be seen. In certain positions, and under certain conditions, they will undoubtedly play a very important part in the needless war which is about to devastate a large portion of Europe.

ORGANIC LIFE.

By H. B. Baker, M.D., of Wenoua, Mich., U.S.

{Continued from page 464.)

THE BEGINNINO OF LIFE. ITS LOWEST FORM, ANT
THR SIMPLEST ORGANISMS—[continued),

~\X7"E com" now to still more complex compounds.
W the fats, consisting of many atoms of each of
the three elements, carbon, hydrogen, and oxygen;
the composition of one of them, stearin, being stated
as Cu4 Hno t)u -^ C'HO. Fats, as they exist in or-
ganisms, are, moreover, compound compounds com-
pounded for, in the higher organisms, they are
made up of various proportions of oleinc, stearin.
and uiargariu. each of which is composed of a base
and a fatty aci'l. as for instance, stearin consists of
glycerine and stearic acid. There seems no limit,
except the mathematical one, to the various propor-
tions hi wliieh those fats may bo combined. In
some tats and oils, glycerine is replaced by other
bases, and there are numerous volatile and other
acids which are peculiar to fats from certain or-
ganisms.

From those facts we should expect just what we find, that the number and variety of ditl'oront kinds of fats and oils are beyond computation. They are peculiar in each particular form of life in which they exist, although more than one may exist in the same organism, for they are sometimes peculiar to a particular tissue. That the oils from the various plants are peculiar to each will be appreciated when it is remembered that many of them are suld under the name of the plant from which they are derived; as rose, peppermint, olive, and castor oils. In animals, wo know that the same is true; fat from the pig is lard ; from the sheep and ox we have tallow, differing slightly in composition.

Most human fat contains a large proportion of margarin. As an example of different kinds of fat in different tissues of the same organism, we may mention the oil and spermaceti which are obtained from different portions of the whale.

The albuminous proximate principles have been considered still more complex compounds.

They have other elements in addition to the throe before mentioned, and consist of carbon, hydrogen, oxygen, and nitrogen; some of them also contain

sulphur and phosphorus in small but definite pro-
portions.

As they exist in the various plants and animals,
and in the different organic tissues, they are vari-
ously modified, although always definite compounds,
and essentially the same hi the same tissue of a
given kind of organism.

The sap of plants, the blood of animals, and, in
fact, each fluid and tissue of plants and animals, is
a definite chemical compound, formed by combina-
tion of such ilotiuito proximate principles as we
have been considering. As the proximate principles
are peculiar to each organism, or, as is sometimes
the case, to each tissue, the tissues formed by their
combination are also peculiar, as, in many cases,
proven by chemical analysis. The fluids and tissues,
of which all organisms are composed, being definite
chemical compounds peculiar to each kind «f or-
ganism, till organUuus may ht considered dtjiiiite com-
jioittuh, tlic- composition bring pt<_ ttliar tu each kind of
oiganimn.

While this is in general terms tme, it is not 'the
whole truth; for, while these simple compounds,
which consist of small proportions of only one or
two elements are strougly marked, stable com-
pounds, not easily destroyed, and capable of little
if any modification, the more complex compounds,
consisting of many atoms of several elements, are,
on the contrary, more unstable, and capable of modi-
fication in various ways. The more complex the
compound, the more easily modified, and the
greater number of modifications possible, and con-
sequently the more numerous the varieties, until, in
those organisms which are extremely complex, no
two individuals are precisely alike. Throughout
their existence, they are also continually undergo-
ing changes caused by surrounding forces acting
upon their easily-modifiable tissues, and are not,
therefore, precisely the same at any two periods of
their existence. This is true of such an organized
whole, considered as a compound, and also of the
several tissues of which it is composed, they being
definite compounds. In fact, the organism is
changed by changing its tissues and fluids, and
they by changing their proximate principles. Those
tissues which are most complex arc most easily
modified, as well as capable of greater variability,
as is seen by referring to the different tissues in the
human body. The bones, teeth, and hair, being
composed of a few small-atomed elements, are com-
paratively simple compounds, and are the most
stable, resisting the surrounding forces long lifter
the softer tissues have disappeared; they are also
less susceptible of modification during life, as their
rate of change is not so rapid; they, moreover, vary
little in different bodies. The brain, on the other
hand, is an extremely complex compound, formed
by the union of complex, fatty, albuminous, and
other compounds. After death, it is one of the first
tissues to decay, and during life it is so easily modi-
fied as to be not precisely the same in any two
individuals, or oven in the same individual at
two slightly separate periods of time. (The same is
soon—although not as plainly—in another way
when races of men are compared : those of the lower
races have hair nearly alike, of one and the s:u:ie
colour, whereas, the higher-organized men of civi-
lized races have hair of various shades. The brain,
and consequently the shape of the heads, of highly-
civilized races of men, varies more than among the
uncivilized).

Beginning with the lower chemical compounds—
alum and ammonia may be modified by substitution
of one element for another, the former by addition
and subtraction of water, &c. Sugar may be modi-
tied by addition or subtraction of the elements of
water. The minute living things, seen under the
microscope, which appear to lie nothing mure nor
loss than particles of albumen, may bo really so, and
still be {of several kinds, as albumen is known to be)
variously modified, according to the organism from
which it is derived. The complexity and consequent
modifiability of organisms are very greatly increased
as soon as any form of fat appears as a constituent.
Oleine, being one of its simple forms, is itself com-
posed of two lower compounds—glycerine and oleic
acid—both quite complex. We find, under the lui-
croscope, great numbers of different organisms,
which appear to be simply albuminous and oily
matter variously modified. The addition of earthy
matters, such as carbonate and phosphate of lime,
furnishes other elements of variability, but not to
such an extent as the addition of the largor-atomed
elements, carbon, hydrogen, oxygen, and nitrogen.
While there is probably only one kind of pure water,
there are several kinds of starch, inauy kinds of
sugar, immense numbers of albuminous compounds,
and an innumerable variety of fats. The power of
variability, beiug so rapidly multiplied by combina-
tion of compounds already variable, we can easily
see that the variety of ways in which such variable
compounds may be combined to form higher ones,
will result in such number and variety as will bo
practically infinite. The human brain being one of
these most complex compounds, it is easily modified
by very slight experiences of force ; and the variety
of changes which may be effected in it, through
action and reaction with its various surroundings,
is beyoud the power of one imagination to conceive
—the imagination of one person being, as is believed.

but the expression of changes possible to lia- .<_ person's brain.

It seems important to fully comprehend tbti n, phenomena attendant upon change's oecaria? a t ganisms, as results of their experience of the far. acting upon them, are dependent upon then str tore, as regards matter and arrangemeot. AUtoethis principle appears to bo well understood in .'i sciences, it stilL^eems necessary" to dwell cohere, for it has been so lon^j and uniicrabit sumed that living organisms are endowed wuiiic special supernatural power, vital force, <a » coiumumcuted to them at their creation and irpiiug from them at death, that Hie notion Inn hx. firmly fixed, and, although held without p\.: difficult to displace without the strongest tr..-: requiring for this purpose a laore or less «sl*. knowledge of the laws which govern or fcpjo •■ changes of matter and force throughout ttr verse, and the phenomena attendant therMc » well is the fact established, in cheniifttry. tb finite chemical compound always acts in ti .. manner under precisely similar condibfis:„ when two substances are found that act Aifer under such conditions, and are found by nu» lie composed of the same elements in the apportions, they arc considered as having av meat of elements peculiar to each : and, i*> try, this is, perhaps, the only satisfactory*? tiou possible. By reason of such different •» ineiit, they are essentially different eoinpoo. stove is a different structure from a steam-c: although made of the same material in the: proportions.

This reference to mechanical structures sen remind us that in mechanics, also, it is well Estood that function depends upon structure," assumption of a vital force peculiar to each mac:-' would be considered ridiculous by all who know b • machines aro constructed; anil yet if a person «■&.■ be supposed to exist having no knowledge of at chines except their external appearaaee and visibk movements, that person might conclude that soar supernatural power impelled them, and that, who. motion ceased, the soul had left thew dead: tht Chinaman's watch that" died last night " illustrates this in a manner. Biologists, physiologists, and all who most thoroughly underst&ud the structure und function of organisms, most, it <*ema to me, l>elieve that in them, as in aU ehemicsl conr$onmd?, and as in mechanical structures, function dje^jtuAs upon structure. Believing with HerWrA. Spene r, that " the doctrine that all organisms are. \rai\l '.» of cells, or that cells are the elements out of «Wii every tissue is developed, is but approximately tra*. There aro firing forms of which cellular stTUcUp cannot be asserted ; and hi living forms that are t' the most part cellular, there are nevertheless to tain portions which are not produced by -■ metamorphosis of cells." "(Principles of Biokp p. 10.)

We may. however, accept the evident* of u eminent physiologist. M. Yirchow, on the svbf of function as dependent upon structure, *taltogother indorsing the cellular hypothe&u «-' he so strongly advocates. "Life," says M. Y=-' "is the activity of the coll; its characters*those of the cell. A cell is a real body, cos*'-'' determined chemical substances, and ciV-' according to determined laws. Its nctiviv*" with the substance kwbich forms it and *•* contains; its function varies, increase* ua cnishes, appears and disappears, w ith the '->-the growth, and the diminution of the su!';? But this matter does not differ in its clement* the inanimate matter' of the inorganic kin*iwhich, on the contrary, it constantly employs top feet itself, and to which it retnrus after liayins ■ complished its special duty. That which is r* I its own is the manner in which the matter » «■ posed of, the peculiar grouping of the minutes''ticles of matter, and yet this grouping is u. pocidiar as to bo in opposition to the dispoMl and groupings which chemistry detects! in iiiorg bodies. That which seems to us peculiar is '• kind of activity; the special functions of orgt substance ; and yet this activity and these fimrhf do not differ from those which natural philojepi' studies in the inorganic world.

"All the peculiarity is confined to tliiA, nam*'' that hi the smallest space are condensed the lew varied combinations of substances, that each e*U the focus of the most iutimate actiuus uf the isvaried combinations, and that it thus produe effects which are met with nowhere else in Xatu.' because nowhere else cau we find a similar intuit of action."*

Again, referring to chemistry, we know that tk freezing and boiling points of liquids, though diftV ing with liquids that differ in constitution, ure riv for each, and are always the same under preei«' similar conditions. Points at which various >c' stances fuse and ignite are fixed and peculiar I each; in fact, there are fixed limits within whk any given chemical change can only occur, FinolV the whole science of chemistry is based upon u one groat truth, that function depends H/hjh x't-4, turc, that any given substance behaves in preeivl

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tho same maimer under precisely similar conditions; otherwise no analysis would be possible, for in what ■Iocs chemical analysis consist ?" The methods of quantitative analysis consist in bringing the substance under examination into contact with other bodies of known properties, and observing the phenomena which ensue." These "other bodies of known properties" are called reagent*, and " the ensuing phenomena are termed reactions." "By menus of reagents, the chemist puts questions to the substance under examination, inquiring whether it contains tlus or that group of chemically similar elements, Or only this or that member of such l^voiip. If the question be put correctly, i. <., if all the conditions under which the reaction expected Cm be produced l>y the reagent employed be carefully observed, the answer is decisive as to the presence or absence of the element or group of elements sought."—(llamlbouh of Quantitative Chemical A.naiijai.1, by Prof. K. C. Kcdzie.)

Since all organisms are definite chemical compounds, we see that the several phenomena which collectively make up the life of an individual organism, and which are similar to the phenomena exhibited by all other organisms of its particular kind, and different from those of any other kind, may be considered as the reaction* which occur in consequence of its being brought " into contact" with its surroundings. In all organisms of a kind these reactions are similar, because all such organisms are similar chemical compounds.

Throughout all Nature we find that function depends upon structure, although, in living organisms, it has been aiaumed to be otherwise. I have endeavoured to point out that all organisms have definite chemical composition, which is, in great degree, essentially similar in all organisms of a kind and differeut in different kinds. In order to correspond with what is recognized in mechanics and other sciences us natural law, and in order to harmonize with the fundamental truth upon which the science of chemistry is based, the individuals constituting each species of organism having similar definite chemical composition should exhibit similar phenomena when exposed to the several reagents which make up their surroundings, and that they do tliis is a fact too familiar to require illustration. _ The individuals of different species or kinds of organisms, having a different composition and structure, should exhibit different phenomena when exposed to the same reagents or surroundings; and this is a wellrecognized fact. Those species most nearly similar in chemical structure should most nearly resemble each other in the phenomena attendant upon their experience, and that they do so is also well known. Those tissues in different organisms which hi structure closely resemble each other should have n corresponding resemblance of function. This fact is strikingly apparent, as we see when we remember that the brain and nervous system have a similar, though not precisely like, composition in all animals, and perform similar functions. The muscles of differeut animals are similar in structure as they are also in function.

A survey of the evidence hails us to the conclusion that the phenomena, reactions, or functions wliich collectively make up the life of an organism must result from its definite composition. In other words, life consists of the phenomena exhibited bydefinite chemical compounds while experiencing conditions compatible with their existence. As the lvnetious of all chemical compounds and mechanical structures are peculiar to each composition or structure, so the phenomena of any organism are peculiar to that organism, and result from the action and reaction between it ami its surroundings. As before stated, "a definite chemical compound reduced to its lowest terms should consist of two equal atoms arranged with the simplest definite relation to each other."

It is intended at a future time to continue the subject by considering the remaining prominent characteristics of living beings and also mutilation of organisms.

ORGANIC MOTION; THE ACCTION OF SOME POISONS, AND THE ESTIMATION OF ORGANIC FOKCE.

Certain motions, not entirely dependent upon external force, are manifested in liviug organisms, and are called Organic Motions. There are several kinds, visible and invisible, such as muscular, causing motion of a part, or of the individual; nervous, inducing muscular and other motions, osmotic and circulatory motions of the fluids; and molecular motion—heat, light, and electricity,

Force is the name given to the cause or producer of motion, and each kind of motion is understood as a mode in which force acts. In order to better understand the source of the force used in organic motions, we will begin with some of the most familiar kinds of matter and force, and rapidly trace them through some of their changes up to the higher-organized forms.

Through the action of the several modes of force —heat, light, attraction, &c.— elementary matter is arranged iuto molecules and crystals ; from these the some forces, through the directing influence of germs, build up the more complex vegetable organisms; the mutter and force stored up in the vegetable uidlower forms of matter are, through the continued

action of these forces, used in constructing the more highly-organized herbivorous animals ; finally, by the further action of the several forces, matter and force, from these previous structures, are still further built up iuto the complex and highly-organized human being. If any of the conditions to the existence of these organisms be withdrawn, they return toward their constituent elements. All the changes have been from stable to comparatively unstable compounds, which, as we have elsewhere seen (When considering the " Laws of Chemical Change "), require force for their continuance. When, through the action of some starting force, these organisms break up, either totally or in part, into lower compounds, they undergo a change from unstable to atalile, and, in accordance with the general law (elsewhere stated), force is liberated. Throughout all Nature the evolution of force is the result of change from conditions wliich required force for their production to conditions requiring less force. All organic motions result from changes, greater or less in amount, from unstable to comparatively stable compounds, requiring force to start them, but liberating force while they continue. These changes are, firBt, rearrangement of the constituent atoms or molecules; and, secondly, combination with other atoms or molecules. The rearrangement may be slight, such as that which in chemistry is termed isomeric, .giving out a small amount of force, ami requiring hut little to regain it* former vital condition, or it may be a more or less complete breaking up into new and lower compounds constituting a mode of decomposition. Probably by far the greater amount of motion result from changes by combination with other elements not necessarily forming a part of the organism, and mainly through union with oxygen. This mode of change may vary from the slight substitution of one atom or molecule for another, to lie in turn replaced by one precisely similar to the first, through the continued action of the organizing forces, up to sufficient decomposition to permanently destroy the organism. In considering the liberation of force, we will follow the same order as when tracing the successively higher forms which are produced through its organizing action on matter; noticing first the crystal, then the plant, and finally the various modes of animal force. Beginning with one element, the atoms definitely arranged by force, we know that when carbon, crystallized in the diamond, is heated to redness, and placed in an atmosphere of oxygen, it unites with it, and in burning gives out 8om<! of the force used in its formation, as moelcular motion, heat and light. A certain amount of heat-force is required to start the change, and certain surrounding eomlitions are essential to its continuance, but under those conditions, the diamond is an unstable furni of matter, and is decomposed to assume a form requiring less force for its maintenance. The decomposition of certain chemical compounds yields electrical and other modes of motion.

It is a well-known fact that the more or less complete decomposition of ordinary vegetable forms is attended by a liberation of force, generally as heat. Wheu the steam-engine is operated by the use of wood as fuel, organic force is used for the movement of machinery; tree-power is made to aid. oris substituted for horse-power, as both of these are used to save the higher form of power exerted by man.

In this case the decomposition of tho wood, bycombination with oxygen, is nearly complete, and the liberated molecular motion is communicated to the water to form steam; but its continuance, as molecular motion, is resisted by the solid though moveable portion of the engine, and a certain portion is thereby converted into motion of a mass. Locomotion is thus rendered possible through the use of only the organic force of plant life. If the diamond were sufficiently plenty to be used as fuel, the same might be accomplished by the force stored up in the crystal. In the sensitive plant (mimosa) we have an interesting example of motion, which may be frequently repeated during its life, as the attendant decomposition, or change, is not. as in the foregoing examples, complete.

In the complete decomposition of animal organisms, force is liberated; but the complex structure of animal bodies renders possible, during life, various simultaneous changes of different characters, occurring in differently-constituted tissues, which have different conditions of stability, and in different portions of the same tissues more freely exposed to force. The great variety of changes which thus occur liberate force in a great variety of modes, causing heat, electricity, nervous, muscular, and other motions. In the higher organisms, such changes normally continue only until a certain portion of the particular tissue or form of matter has undergone this change, for the complete withdrawal of one essential element from an orgamsm is equivalent to its decomposition. During the continuance of such changes force is manifested, and, in time, by the continued supply of proper matter and several forces, the organism is again restored to about its original condition, when it is again possible for force to he liberated upon experience of the proper starting-force. By a certain set of changes, by replacement or substitution, these phenomena of force may at intervals recur. If the

replacement be made by substance not capable of, in turn, giving place to the proper matter under the natural couilitions, then the succession of changes is interrupted, and if this abnormal substitution be complete and permanent, death must result; for, if an essential element combine with foreign matter, it is equivalent to its removal, and this involves the destruction of the organism. Thus, if, in passing through the lungs,' the Wood gives off carbonic acid, and, instead of meeting with oxygen, combines with sonic other element, as, for instance, chlorine, not capable of going through the changes in the tissues essential to the continuance of life, death mnst result. Many poisons, such as hydrocyanic and other acids, alkalies, etc.. may cause death by combining with and refusing to release essential elements of the organism. It seems quite probable that tho acids of arsenic may act by thus combining with the iron of the blood. This theory is supported by some facts, among winch are, first, the colour of the blood is in great degree due to iron; the use of arsenic in sufficient quantities, for a length of time, causes a certain paleness of the complexion; and, secondly, hydrated-peroxide of iron has been found to be the most effectual antidote, and is supposed to act by combining with the arsenic to form a compound insoluble iu the nimbi of the alimentary canal. May not a similar compound of arsenic and iron he formed in the blood, and. if not insoluble, incapable of giving up the iron to go through its proper changes in the body?

The amount of force given out during any change depends upon the nature of the change, and cannot lie determined from the result of any other change not precisely the same in character. In illustration: natural "forces organize carbon and other elements into wood, and by its partial destruction charcoal remains; they form the compound nitrate of potassa; additional force is employed by man in pulverizing and mixing charcoal, sulphur, and nitrate of potassa, to form the highly-iuistable substance, gunpowder: the application to this of a proper force starts a chemical change, and more stable compounds are formed, liberating the amount of force, stored up hi it, less the amount necessary to form and maintain the lower compounds. No experiments with the changes of carbon, sulphur, and potassa, or even with those occurring in compounds of those elements combined in any other way, enable us to determine the amount of force liberated during the combustion of gunpowder. It seems improbable that the amount of force given out by any change occurring in the brain can be properly estimated from any experiment with ordinary carbonaceous or nitrogenous compounds.

It can oidy be experimentally determined by a precisely similar change in a compound chemically the same, where the lower compounds formed shall be the same in character as those formed in the brain. The same may he said of a change occurring in the muscular substance or in any tissue or fluid of the body. Inasmuch as the different tissues and fluids have not chemically the same composition, the changes occumng in them may not bo similar; they probably are, to a certain extent at least, peculiar to each; so that if the amount of force liberated by a certain change in the blood be known, the fact will not serve to prove the amount liberated by a change occurring in any other part of the body, unless the nature of the changes is known to be the same. As force is indestructible, the amount used in building up any compound, when no louder acting to maintain it, will, in some form, appear. "The force liberated by the fall of a body is equivalent to the force required to raise the'bodv to the height from which it fell."

The amount of force liberated by any change occurring in an organism must equal the amount required to build up, from the chemical elements, the unstable compound undergoing the change, less the amount required to form and maintain the lower and more stable compounds formed during the change.—from the Journal of Psychological Medicine.

VOLCANOES.

IN a lecture upon tliis snbject, delivered in connection with the Sunday Lecture Society, Mr. David Forbes, F.R.S., &c, said that, although he imagined that but very few of his bearers ever witnessed a volcano iu eruption, all must have read accounts of such phenomena. As a geologist, he might be pardoned regretting I), at we do not possess even a single example of an active volcano in our happy isles. If the question were asked, •• What is"a volcano?" the simplest reply would be, "A hole hi the ground deep enough to reach such portions of the interior of the earth as are in a molten condition." The eruption of Etna in 18bT>, which the speaker witnessed, did not proceed from the summit or inuiii crater, but broke out on the side of the mountain, about 5,416 feet above the level of the sea. Along the fissure formed by the convulsion, no less than seven distinct cones rose up at intervals, building themselves up very rapidly irom th« enormous quantities of scon;e which were

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thrown up at their vents. Uniting in" action, they, in a short time, formed a range of hills several hundred feet in height, and entirely changed the character of the scenery of that part of the island. The formation of a new, or the re-opening of an old, volcanic vent is usually accompanied hy a terrific explosion. In 1812 the outburst of the volcano of Saint Vincent was heard in South America, some 700 miles distant. The enormous force developed hy the rush of gases and vapours from the fissure may he imagined, when it is known that in the eruption of Mount Ararat in 1840, huge blocks of rock, weigliing as much as 25 tons, were thrown out of the crater. Cotopaxi is said to have hurled a 200-ton rock to a distance of nine miles: whilst the volcano of Antuco, in Chili, in 1828, discharged stones to a distance of about 3(i miles from its orifice. The chemical composition of the gasiform emanations from volcanoes proves that they are in greater part incombustible, and therefore does not support the idea that the body of such a column of vapour and gases could he in flames—i.e., actually burning. On the outside of the column, however, innumerable brilliant scintillations arc seen, of a bluish colour, due to particles of sulphur taking fire as they come into contact with the outer air, and patches of melted sulphur are splashed about, brightly burning as they fall down through the air on to the slope of the cone. The buried cities of Stabire, Herculaueum, and Pompeii, covered in parts to tho depth of 100ft. by the ashes of Vesuvius, are ocular proofs of the vast quantities which can be discharged out of a volcano vent during an eruption. A French geologist has estimated that tho volcano of Bourbon has, in the course of only two days, thrown out no less than :100,000 tons of ashes. In that greatest of mountain ranges, the Andes, commencing from the oldest period of their elevation, we find a Beries of eruptive rocks breaking through the sedimentary strata on their flanks, as follows :—

1. The Auriferous granites—probably at the end

of the Devonian period;

2. The characteristic Porphyrites of tho Oolitic

age; 8. The Auriferous Diorites, disturbing the Cretaceous formation; then,

4. The Miocene basalts; aud, lastly,

5. The lavas from the present volcanic forms,

which occur at intervals along the whole range, from Terra del Fuego in the south, all through tho Cordilleras of Soutli aud Central America, up to the Rocky Mountains.

In answering the question as to what force has played the most prominent part in determining the external configuration of the earth, the unbiassed geologist, said the lecturer, must necessarily grant the first place to the internal volcanic or cataclysmic agencies, since, had it not been for their operations, our globe would still have remained a comparatively smooth sphere.

MECHANICAL MOVEMENTS.

[Continuedfrom page 464.)

OfiO French invention for obtaining rotary AUt/< motion from different temperatures in two bodies of water. Two cisterns contain water: that in left at natural temperature and that in right higher. In right is a water-wheel geared with Archimedean screw in left. From spiral screw of the latter a pipe extends over and passes to the under side of wheel. Machine is started by turning screw in opposite direction to that for raising water, thus forcing down air, which ascends in tube, crosses and descends, and imparts motion to wheel; and its volume increasing with change of temperature, it is said, keeps the machine in motion. We are not informed how the difference of temperature is to be maintained.

270. Steam hammer. Cylinder fixed above and hammer attached at lower end of piston-rod. Steam being alternately admitted below piston aud allowed to escape, rises and lets fall the hammer.

271. Hotchkiss's atmospheric hammer; derives the force of its blow from compressed air. Hammer head, C, is attached to a piston fitted to a cylinder, B, which is connected by a rod, D, with a crank. A, on the rotary driving-shaft. As the cylinder ascends, air entering hole e is compressed below piston and lifts hammer. As cylinder descends, air entering hole e is compressed above and is stored up to produce the blow by its instant expansion after the crank and connecting-rod turn bottom centre.

272. Grimshaw's compressed air hammer. The head of this hammer is attached to a piston, A, which works in a cylinder, B, into which air is admitted—like steam to a steam engine—above and below the piston hy a slide-valve on top. The air is received from a reservoir, C, in the framing, supplied by an air-pump, D, driven by a crank on the rotary driving shaft, E.

273. Air-pump of simple construction. Smaller tub inverted in larger one. The latter contains water to upper dotted line, and the pipe from shaft or space to be exhausted passes through it to a few inches above water, terminating with valve opening upward. Upper tub has short pipe and upwardlyopening valve at top, ond is suspended by ropes from levers. When upper tub descends, great part of air within is expelled through upper valve, so that, when afterwards raised, rarefaction within causes gas or air to ascend through the lower valve. This pump was successfully used for drawing off carbonic acid gas from a large aud deep shaft.

274. .Eolipile or Hero's ateam toy, described by Hero, of Alexandria, 180 years B.C., and now regarded as the first steam engine, the rotary form of which it may be considered to represent. From the lower vessel, or boiler, rise two pipes conducting steam to globular vessel above, and forming pivots on which the said vessel is caused to revolve in the direction of arrows, by the escape of steam through

a number of bent anus. This works on tuc sj» principle as Barker's mill, 438 in this tabli.-.

275. Bilge ejector (Brear's patent) for disciiir. ing bilge-water from vessels, or for raising aadJing water under various circumstances. D 31 chamber having attached a suction-pipe, B, indfr charge-pipe, C, and having a steam-pipe enteral one side, with a nozzle directed toward the disrk* pipe. A jet of steam entering through A M^ 3 air from D and C, produces a vacuum n & »causes water to rise through B, and /** JN* D and C, in a regular and constant urns ''* pressed air may be used as a substitoifa*'11

276. Another apparatus operating ft a s" principle as the foregoing. It is tens*'*85 siphon pump (Lansdell's patent). Awtef-W B B, are two suction-pipes, having a fesi*8*" uection with the discharge-pipe, C. The asst pipe entering at the fork offers no obsUtte W» upward passage of the water, which moves *pLl in an unbroken current.

277. Steam trap for shutting'in steam, bslf viding for the escape of water from steamefiti?« radiator (Hoard & Wiggins patent). It eMMaf"" a box, connected at A with the end of th* «iJ the w aste-pipe, having an outlet at B, and foreS" with a hollow valve I), the bottom of which isc posed of a flexible diaphragm. Valve is fiErd r: liquid, aud hermetically sealed, and its <h»p'e' rests upon a bridge over the outlet-pipe. Tin F sence of steam in the outer box so heats tils'* in valve that the diaphragm expands and n* valve up to the seat, a, a. Water of condeiftaccumulating reduces the temperature of' and as the liquid in valve contracts, diapallows valve to descend and let water off.

278. Another steam trap (Bay's patent). "\ a closes and opens hy longitudinal expanse contraction of waste-pipe. A, which terminate: the middle of an attached hollow sphere, I' portion of the pipe is firmly secured to n fixed * port, B. Valve consists of a plunger whioh «*' in a stuffing-box iu the sphere opposite the end J a pipe, and it is pressed toward the end of the pij»r! a loaded elbow lever, D, as far as permitted to stop-screw, b, and stop c. AVhen pipe is filled *^ water, its length is so reduced that valve remit' open; but when filled with steam, it is expands * that valve closes it. Screw, b, serves to adjust u action of valve.

279. Gasometer. The open-bottomed vessel. J is arranged in the tank, B, of water, nnd parti counterbalanced by weights, C C. Gas enters li gasometer by one and leaves it by the other of tl two pipes inserted through the bottom of the ton) As gas enters, vessel A rises, and n>c peraa, lb pressure is regulated by adding to or reducing t-i weights, C, C.

(To be continued.)

Benzine is said to render ordinary paper tr&E: parent nud suitable for tracing purposes.

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THE RUDDICK STEAM ENGINE.

fflHE accompanying illustrations of this engine I are taken from the American Artt»aji. The piston heads, A A. are rigidly connected by four rods, the two upper ones showing at F F. These rods insure an equal motion of the two piston heads in the same direction and at the same time. The piston being thus extended by these rods, admits of the interposition of the connecting rod B, from a wrist-pin in one piston head to the crank shaft, C, which runs transversely through the cylinder, carrying on one end the belt or fly-wheel, and operating on the other the valve stem, D, which is moved by the short arm, E, attached to a crank pin on an adjustable collar fitting on the crank shaft. The valves and steam chests ore represented at H H.

The advantages claimed for this engine are :—

1st. Extreme simplicity, beyond any other make of engine. A reference to the annexed plan and explanation readily confirms this. This quality of simplicity insures—

2nd. Fewer parts, and each part contributing directly as a medium of power, and consisting only of the cylinder, piston, connecting rods, crank, valves, and valve stem.

3rd. Greater saving in repairs, on account of the fewer parts, and equal durability as compared with the best engines.

4th. Greater economy in space and weight than any other engine, and consequent economy in transportation. A 1 j-horse power engine, weighing less than 1,0001b., is included within a space of 42in., longest measurement, all set up with belt wheel, Sec, ready to run.

5th. Can be ran in any position, and at any reasonable speed. The cylinder must preserve the same right line, and the engine requires no foundation.

6th. Greater economy in use, not only from saving in repairs, but the few and simple parts in this engine do not require an experienced engineer to run and keep it in order. Any intelligent boy of fifteen could be taught to run and take all needful care of one in a day's instruction.

7th. Its simplicity insures cheapness of construction, and consequent reduced cost to purchasers, while at the same time its cheapness does not in the least particular affect its power and usefulness. Ou the contrary, its simplicity is a positive mechanical gain, using, as it does, every necessary port, and discarding all that are not directly, and in the shortest line, mediums of power. The consumption of power in the engine itself is unavoidably less, and the amount transmitted to the distributing point in like degree greater than in the case of any other engine.

It can be made of any power, from one-half horse power or less, to any required size.

WAR AND WATER.

1I1HAT inability to apply the principles of logic, or 1 insufficient confidence in the soundness of those principles, not unfrequently causes conclusions to be drawn which scarcely follow from the premises has 1 ong been known; thus, we are told, that in the reign of Ahdallnh m. there was a great drought at Bagdad,

and that although the Mohammedan doctors issued a decree that the prayers of the faithful should be offered up for rain the drought continued. The Jews were then permitted to add their prayers to those of the true believers, but the supplications of both were ineffectual. As famine stared them in face, those dogs, the Christians, were at length enjoined also to pray. It so happened that torrents of rain immediately followed. The whole conclave, with the mufti at their head, were now as indignant at the cessation of the drought as they were before alarmed at its continuance. Some explanation was necessary to the people, and a holy convocation was held; the members of it came to the unanimous determination that the God of their prophet was Highly gratified by the prayers of the faithful, that they were as incense and sweet-smelling savour unto him, and that he refused their requests that he might prolong the pleasure of listening to their supplications j but that the prayers of those Christian infidels were an abomination to the Deity, and that he granted their petitions the sooner to get rid of their loathsome importunities. Some conclusions about as logical have just been published by Mr. Ch. Le Maout, pharmacist, of St. Brieuc, in consequence of the drought we have recently experienced.

The connection of war and water is perhaps not studied by military officers generally, except so far as relates to the transport of large bodies of troops across seas and rivers; whilst the conclusion drawn by most non-military persons would be that the discussion of war and water must relate exclusively to naval warfare. If we accept the doctrine of Mr. Le Maout, we shall learn what lamentable results such ignorance may lead to. As Mr. Le Maout is the author of a work entitled t; The Cannonades of Subastopol, or the Cannon and the Barometer," published in 1866, it appears that he has occupied himself for some time with the question; and he considers that his observations, made during the Russian war, and published at the time, establish in an unequivocal manner the condensing action of cannon upon cloud, and consequently their effect upon barometrical indications. This action was constantly observed iu Brittany in from 100 to 120 minutes, although the distance from the seat of the war was more than 600 leagues as the crow flies. During the formidable cannonades of the seige of Sebastopol|he noticed that generally— n Brittany we presume—whenever the firing commenced the azure of the sky was overcast, and a fine rain or mist fell, frequently followed by heavy showers and then by wind. Afterwards, and as a consequence of these condensations, the barometrical column was put in motion, and rose at a speed and to a height proportional to the extent of the cannonade. The record of the barometrical indications represented pretty exactly the extent of the firing when the effect was not modified by some great physical phenomena, such as a volcanic eruption or u great tire. Then the rarefying force neutralized the condensing force, and the barometer remained stationary until one or the other conflicting forces ceased to operate. But still more marvellous, and what attests the extreme sensibility of the instrument, he observed, that after six memorable engagements, followed by armistices of two or three hours con eluded for the burial of the dead, the barometer stopped, and remained stationary during the whole

tune the burial was going on; then, just after tw > or three hours, at the moment when the cannonading recommenced, the column again gave signs of movement upward, and by its speed made up for lost time. It was this remarkable property that enabled him to calculate the exact time that was required for the force applied in the Crimea to exert its influence in Brittany.

And it is not cannon alone that possesses this condensing action. Mr. Le Maout has found that the explosion of mines and powder-mills, and even the sound of bells, produce a similar effect. Even the simple striking of a village clock, and of those of churches and chapels, suffices, on the coast of Brittany, where they have almost constantly a humid atmosphere, to make the rain fall; but for this certain physical conditions are necessary. The wind must be blowing from the south-west and carrying rain-cloud, and the barometer must stand below 76 centimetres. In this state of things, when the temperature is not high, it is rarely that the striking of the hours does not show its condensing action upon the aqueous vapour, especially when the clouds are low, for the vibration of bells and of clocks striking only acts within a limited area. In the month of May, 1856, the year of the great inundations, he carefully observed the exact time of the fall of the rain, and found that, ont of 133 times that it rained in the month, the fall occurred 76 times at the striking of the hours, 42 times at the half-hour, 8 times at the three-quarters, and 7 times at the quarter. He considers that it is the intensity of the sound, as well as the repetition, that has the most powerful effect upon the condensation of the vapour of water; and he explains that such observations cannot be made in Paris and other large towns, where so many noises are produced from fortuitous or accidental causes between the times of the striking of the clock's. Speaking generally, he maintains that all noises produced by physical or artificial causes result in the condensation of aqueous vapours. Thus the beating of the drum, and the sound of military music where brass instruments predominate, produce identical effects, and it is the same with heavily-laden wagons passing over paved streets, and with trains of loaded trucks on railways. The vapour of water being formed of myriads of vesicles of the smallest diameter, similar as to their fragility to soap-bubbles, it is not surprising that, by the powerful percussion of the ai-rial mass, they should break, and resolve themselves into rain. When we are enveloped in this vapour by a sky charged with rainclouds, we are in a most impressionable medium, which for its fragility, may be compared to a palace of glass. If, under these circumstances, we fire a cannon, all will be smashed to atoms, and necessarily fall about our ears. If, however, there be nothing above us but the azure of heaven, we may fire cannon and ring as long as we like, yet nothing will fall. "It is this," says Mr. Le Maout, "that the adversaries of my doctrine of condensation will not understand; they wish, as proof of the truth of it, that rain shall fall under all circumstances."

Now, were this the sole objection to Mr. Le Maout's hypothesis, he would certainly have grounds of complaint, for it must be acknowledged that there are many experiments which can only be

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